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cbag lec 2
| Question | Answer |
|---|---|
| What are the main lipid types in biological membranes? | Phospholipids, sterols, fats & oils, and waxes. |
| What is the function of phospholipids in membranes? | They form the bilayer structure, with hydrophilic heads facing outward and hydrophobic tails inward. |
| : What is the role of sterols (e.g., cholesterol) in membranes? | They help regulate membrane fluidity and are unique to eukaryotic cells. |
| What is the primary function of fats and oils in cells? | Energy storage, mainly as triglycerides. |
| What is the function of waxes in membranes? | They serve as protective coatings. |
| What is the Fluid Mosaic Model? | A model describing membranes as fluid structures where lipids and proteins move dynamically. |
| How do lipids move in the membrane? | They diffuse rapidly within the bilayer, contributing to membrane fluidity. |
| What are lipid rafts? | Cholesterol-rich regions that play roles in signaling and protein sorting. |
| What are the three types of membrane proteins? | Integral membrane proteins – Embedded in the bilayer. Peripheral proteins – Loosely attached to membrane surfaces. Lipid-anchored proteins – Tethered to membranes by lipid tails. |
| What is a key characteristic of integral membrane proteins? | They span the bilayer and have hydrophobic regions interacting with lipid tails. |
| How do peripheral proteins associate with the membrane? | They attach to integral proteins or lipid head groups and can be easily removed. |
| What is selective permeability? | The ability of a membrane to allow certain molecules to pass while restricting others. |
| What are the types of passive transport? | Simple diffusion – Movement from high to low concentration. Facilitated diffusion – Transport aided by membrane proteins. Osmosis – Water movement across membranes based on solute concentration. |
| What is active transport? | Movement of molecules against their concentration gradient, requiring energy (ATP). |
| Give an example of active transport. | The Na⁺-K⁺ pump, which moves sodium (Na⁺) out and potassium (K⁺) in against their gradients. |
| Do integral proteins change orientation within the membrane? | No, but they can move laterally within the bilayer. |
| What are lipid rafts, and why are they important? | They are cholesterol-rich microdomains involved in cell signaling and protein organization. |
| What is the primary structure of biological membranes? | A phospholipid bilayer with embedded proteins. |
| Why are membrane proteins important? | They are crucial for transport, signaling, and structural support. |
| What property of lipids is essential for membrane function? | Their amphipathic nature, allowing bilayer formation. |
| How does selective permeability benefit cells? | It helps maintain homeostasis by regulating molecule passage. |
Created by:
REDZ17
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